This is a great series for children who like "snippets" of information, and the series covers a HUGE range of subjects. These books present information in a very easy-to-read format - it doesn't need to be read in any order; a child can just flick to a page and read a little fact. Children who like trivia like Guinness World Records books will like this series, too.
These books would be useful when beginning to teach primary school children how to do basic research and write short reports.
These books are often reprinted every few years, with updated graphics and appealing layout (I'm sure updated information if needed, too), so I'd recommend looking for the most recent edition if you can.